Sterilizing method and sterilizing package



Feb. 10, 19-70 w. BARASCH 3,494,725

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INVENTOR. 3 WERNER BARASCH BY Mumm ATTORNEYS United States Patent 3,494,726 STERILIZING METHOD AND STERILIZING PACKAGE.

Werner Barasch, Los Gatos, Calif., assignor to Becton,

Dickinson of California, Inc., Los Gatos, Calif., a corporationbf California 1 Filed Dec. 27, 1966, Ser. No. 604,776

Int. Cl. A61] 3/00 US. CI. 2158 9 Claims ABSTRACT OF THE DISCLOSURE A portable compact sterilizing package for the rapid sterilization, of surgical and medical objects at a location local arid remote to the packaging location. The package includes a lightweight, gas-impermeable, sturdy container. An object to be sterilized is positionedwithin the containeralong with a substrate. Means are provided for isolating the substrate from the object within the container and a sterilant gas is heat releasably bonded to the substrate. The sterilant gas is quickly released by the application of heat to the exterior of the container so as to come into contact with the object within the container and rapidly sterilize the object. The container is gasimpermeable to prevent sterilant gas from escaping the container and contaminants from entering the container at any time prior to the opening thereof for use of the sterilized object contained therein.

The present invention relates to the use of sterilant gases in a closed package containing the object to be sterilized. A carrier or substrate is provided carrying the sterilant gas by means of a releasable bond so that after packaging the article the sterilizing operation can proceed. This enables the sterilization of surgical instruments and equipment, and the like, to provide pre-packaged sterile objects at the site of packaging with great savings on equipment, shipping, and handling. It also provides for sterilizing objects after use of such objects in the field, for example, in field hospitals.

Known sterilizing methods used in hospitals and surgical supply businesses include placing the objects in autoclaves and sterilizing with steam or gas of varying pressure, and these known methods require more or less expensive stationary installations and often require shipping of the articles from the place of manufacture to distant treating plants.

The present invention obviates certain major disadvantages of the known methods and has for its general object provision of a pre-packaged sterile object at the site of packaging where the sterile object is enclosed in a container which is impervious to bacterial contaminants although it may be gas-pervious with a gas sterilant so as to enable rapid and efiicient sterilizing of the object to be sterilized either individually or in groups.

It is therefore, a general object of the invention to provide a sterilizing package and a sterilizing method which enable sterilizing of various surgical and medical objects such as gloves, forceps, scalpels, clamps, sutures, syringes, bandages and other objects at the point of manufacture Without reference to a particular sterilizing installation or sterilizing equipment.

Another object of the invention is to provide an improved method of sterilizing objects by placing them in a sterilizing package which is useful at a manufacturing plant or in the field.

Another object of the invention is to provide a selfsterilizing packaged article.

Other objects and advantages of the invention will be apparent from the following description of certain pre- 3,494,726 Patented Feb. 10, 1970 ferred embodiments thereof taken in connection with the accompanying drawings, in which:

FIG. 1 is a front elevational view of a closed bag ready for a sterilizing operation;

FIG. 2 is a sectional view taken along the line 2-2 in FIG. 1; and

FIG. 3 is a front elevational view of a modified form of the invention.

The sterilants to be used in accordance with the instant invention are the known sterilant gases such as formaldehyde, ethylene oxide, beta-propiolactone, propylene oxide and phenol. The sterilant gases are bonded physically with non-flowable substrates or carriers, either solid or viscous pastes, such as activated alumina (such as used in chromatographic columns and sold under laboratory names such' as CENCO), silica gel (activation optional; grade used was also chromatographic adsorbent, 30-60 mesh, Mathe son, Coleman and Bell), activated charcoal or celluloses (such as blotting paper or methylcellulose), or other substrates capable of forming a releasable bond with the sterilant such as methylene glycolstarch, methylene glycol-melamine, methylene glycolethanolamine or paraforvmaldehyde (heated), said bonds being of releasable character to enable release of the sterilant gas when desired. These bonds as noted may be either physical bonds or chemical bonds which are weaker than the normal chemical bonds and capable of breaking by thermal energy to cause diffusion of such gases, either at ambient or slightly higher temperatures. Bonds capable of such breakage are usually weaker than about 10 kilocalories per mole. However, in the case of stronger bonds, such bonds may be broken and cause release of the gas by a shift of equilibrium brought about by a change in temperature or concentration or by the action of a catalyst. The catalyst may be any suitable acid which will not be harmful in the environment, such as for example, citric, gluconic, and phosphoric acids.

In carrying out the method of the invention, the sterilant gas is bonded to the substrate or carrier and is preferably placed in a gas-permeable bag, such as a paper bag, which forms a barrier against contamination of the article by contact with the substrate itself, and also forms a barrier to the entry of bacterial contaminants. The article or articles to be sterilized are then placed, with the bag containing the gas-carrying substrate, in a container and the container is then closed tightly to exclude contaminants and to contain or substantially contain the sterilant gas within the container. The container may be of flexible or rigid plastic, paper, cardboard or glass with a metal or plastic lid, and it may either be reusable or disposable in character.

Referring to the drawing, FIGS. 1 and 2 illustrate a form a package or bag which is adaptable for use with surgical instruments or other devices which normally have sharp cutting edges exposed, and this package or bag may be a rectangular plastic bag 10 of heat-scalable character in which a sheet of cardboard or similar material 11 is inserted. The sheet 11 is provided with an overlapping bent portion 11a at one end, forming a closed end for reception of the sharp end of an instrument such as a surgeons scalpel 12. The gas-carrying substrate is shown at 13 on the opposite side of the cardboard sheet 11 from that adjacent to the article to be sterilized. The ends of the bag 10 are heat sealed to form closures as at 10a. The thickness of the walls of the bag, the sheet 11 and the substrate 13 placed on the cardboard insert 11 are exaggerated as to size.

FIG. 3 shows a characteristic package as provided for articles which do not have sharp cutting edges and, in this instance, the bag 20 has placed therein a smaller bag 21 containing the gas-carrying substrate and contains a pair of surgeons gloves 22.

The following examples are illustrative of the invention.

EXAMPLE I On a Rotowarp automatic packaging machine, packages were made containing each: one surgical glove, one spore strip holding B. stearothermophilus on polypropylene, and one strip of pressed cellulose sheet (blotting paper) 1" x 2" x 2" into which had been absorbed by contact 04 g. of a 71% aqueous urea-formaldehyde precondensate of molecular ratio 1:5. The spore strip as utilized in this test was a means of introducing bacteria to be killed by the sterilization process. The package made by the Rotowrap machine, in this example, was a 6" x 9" flat package made by heat sealing edges of two sheets of paper, one carrying a sealing compound and the other being gas-permeable. The pressed cellulose sheet was placed in a 1.25" x 2.25 bag similar to the 6" x 9" bag, in both cases the gas-permeable paper or paperboard is about .03" thick and is impervious to bacterial contaminants. The urea-formaldehyde precondensate used was a liquid consisting mainly, as far as is known, of (CH OH) NCON(CH OH) subject to decomposition, with formaldehyde release, to

(CH OH) NC ONHCH OH+ HCHO (g) After two days at room temperature, sterility tests showed negative for bacteria in thioglycollate medium and for spores in Sabouraud medium up to ten days incubation each, signifying that sterilization was complete.

EXAMPLE II The same reagent and control system as in Example I was used on a surgical forceps enclosed in a polyvinyl chloride plastic bag, which was dipped 20 seconds in hot (90 C.) water for instant release of the sterilant gas. The plastic bag was sealed by means of a twisted wire seal. The reagent in this example was brushed on a cardboard blotting paper laminate on the blotting paper side, and the cardboard side carried instructions as to how to use and reuse the bag. The next morning, sterilization was found complete as above described.

EXAMPLES III TO XII The same surgical package and control system as in Example I was used for the following combinations, which Where shown to be equally effective sterilants. In the case of non-aqueous reagents, 3 drops of water was added to obtain the necessary moisture for sterilization. A small gas-permeable paper bag contained the reagents.

sterilant Gas Reagent-Adsorbent III Beta-propiolaetone Cotton.

IV do Activated alumina.

V Formaldehyde Methylene glycol-starch (a solid).

o Methylene glycol-melamine ta solid). do Methylene glycol-ethanolamme (cotton). do.- Paraformaldehyde (heated, a solid). Ethylene oxide- Silicagel.

X Propylene xide Activated charcoal.

XI--. -do Cotton.

X1I Pheno Do.

tion. Where more rapid sterilizing is desired the application of heat to a greater extent can be used, for example, up to C. where a few seconds will eifect the sterilization as is well known in the sterilizing trade.

While I have described a preferred sterilizing package and preferred method of sterilizing articles utilizing a package containing a gas sterilant it is obvious that the invention is capable of variation and modification from the forms shownas well as capable of use with other gas sterilants and other substrates, the scope of the invention therefore should be limited only by the proper scope of the claims appended hereto.

I claim:

.A portable, compact sterilizing package for the relatively rapid sterilization of surgical and medical objects at a location local and remote to the packaging location comprising;

a lightweight, gas-impermeable, sturdy container;

an object to be'sterilized within said container;

a substrate disposed within said container;

means for isolating said substrate from said object within said container during handling, shipping, storing and sterilizing procedures;

a sterilant gas being heat releasably bonded to said substrate; said sterilant gas being quickly released by the application of heat to the exterior of said container so as to come into contact with said object within said container and rapidly sterilize said object; and

said container being gas-impermeable to facilitate the prevention of any sterilant gas from escaping said container and contaminants from entering said container at any time prior to the opening thereof for use of the sterilized object contained therein.

2. The invention in accordance with claim 1 wherein a gas-permeable barrier is provided between the object to be sterilized and the gas carrying substrate.

3. The invention in accordance with claim 1 wherein the substrate includes a folded sheet with the folded portions overlapping the object to be sterilized, and the sterilant gas material is located on the side of the sheet opposite to the side contacting the object to be sterilized.

4. The invention in accordance with claim 1 wherein the substrate and the sterilant gas is carried in a gaspermeable container in a second container within the first container.

5. The invention in accordance with claim 1 wherein said sterilant gas is bonded to said substrate by bonds having an energy of less than 10 kilocalories per mole of gas.

6. The invention in accordance with claim 1 wherein said sterilent gas is released for sterilization purposes when the package is subjected to an exterior temperature of approximately 90 C.

7. The invention in accordance with claim 1 wherein the substrate is of an activated charcoal material.

'8. The invention in accordance with claim 1 wherein the substrate is of a cellulose material.

9. A method for the relatively rapid sterilization of packaged surgical and medical objects at a location local and remote to the packaging location comprising:

placing the object to be sterilized within a lightweight,

gas-impermeable, sturdy container;

disposing a substrate within said container;

isolating said substrate from said object within said container during handling, shipping storing and sterilizing procedures;

heat releasably bonding a sterilant gas to said substrate with said sterilant gas being quickly released by the application of heat to the exterior of said container so as to come into contact with the object within said container and rapidly sterilize said object; and having the container gas-impermeable to facilitate the prevention of any sterilant gas from escaping the container and contaminants from entering the con- 5 6 tainer at any time prior to the opening thereof for 3,247,957 4/1966 Kernble 206-632 3,380,884 4/1968 Dougherty et a1. 21--58 XR use of the sterilized object contained therein.

References Cited UNITED STATES PATENTS MORRIS O. WOLK, Primary Examiner 5 R. E. SERWIN, Assistant Examiner Carnarius et a1. 

